1. Field of the Invention
The present invention relates to actuation, and more particularly to rotational actuation, for example to turn a shaft about its axis.
2. Description of Related Art
A variety of devices are known for actuation. For example, servos, stepper motors, hydraulic or pneumatic pistons, and associated linkages and gears can be used to provide actuation for rotating, pivoting, sliding, and the like. A typical servo, for example, includes a motor, a gear reduction system, and sensors with associated circuitry for feedback control of the motor.
As there is pressure to make products smaller and less expensive, there is an ever present desire to make actuators more simple, compact, and at lower cost. The aerospace industry is one example where size, cost, and complexity are very important. One exemplary actuator, disclosed in U.S. Pat. No. 4,761,955 to Bloch, which is incorporated herein by reference in its entirety, uses a shape memory alloy wire wound through six sets of pulleys of a rotary accumulator as the basis for an actuator.
Such conventional methods and systems have generally been considered satisfactory for their intended purpose. However, there is still a need in the art for actuators that allow for improved simplicity, size, cost, and the like. There also remains a need in the art for such actuators that are easy to make and use. The present invention provides a solution for these problems.